Fastest way to write huge data in file

Question

I am trying to create a random real, integers, alphanumeric, alpha strings and then writing to a file till the file size reaches 10MB.

The code is a

Answer 1

The while loop under main calls generate_alphanumeric, which chooses several characters out of (fresh randomly generated) strings composed of twelve ascii letters and twelve numbers. That's basically the same as choosing randomly either a random letter or a random number twelve times. That's your main bottleneck. This version will make your code one order of magnitude faster:

def generate_alphanumeric(self):
    res = ''
    for i in range(12):
        if random.randrange(2):
            res += random.choice(string.ascii_lowercase)
        else:
            res += random.choice(string.digits)
    return res

I'm sure it can be improved upon. I suggest you take your profiler for a spin.